During the past 10 years, the Community-Based Participatory Research Project (CBPR) of our Center has worked with community groups and individuals to examine the take-home pathway of pesticide exposure among children of farmworkers in Yakima Valley. The CBPR study provided evidence that demonstrated children's exposure through a para-occupational pathway and in the previous 5 years of this Center grant, the CBPR Research Project conducted a community based intervention project (CIP) that identified and successfully implemented an intervention reducing the occupational take home pesticide exposure pathway for families and their children. These findings led to a number of additional questions on the part of our community partners; specifically, are there other pathways of pesticide exposure and are non-farmworkers exposed to pesticides. This proposed renewal project is designed to find answers to these questions. In this project, the CPBR investigators will characterize the seasonal variability of organophosphate (OP) exposure across our cohort by sampling at times of peak OP usage and by evaluating OP metabolite profiles across time during these seasons; assess the influence of gene environment interactions on OP exposure and response profiles; and calculate the contributions from gene, environment and season to within-person and between-person variability of the urinary OP metabolites in farmworkers to identify quantitatively differences between persons and across seasons. Secondarily, CBPR investigators will build from the recent observations by our colleagues in the Pesticide Exposure Pathways Research project that measure parent and oxon concentration for 3 OPs during times of peak agricultural usages. The current studies revealed that measurable CP and CPO levels that were obtained were different than current air models would predict; further, they appear to contribute a proximity factor to our cohort exposure studies. Thus we will coordinate our cohort and household sampling with agricultural practices and field air monitoring.